One-step or two-step screening for thyroid diseases during early pregnancy: which is better? / 中华围产医学杂志

ABSTRACT

Objective To investigate the appropriate screening method for thyroid diseases during early pregnancy.Methods We collected information of 4 044 pregnant women who attended to the Department of Obstetrics and Gynecology of Peking University First Hospital from September 1,2013 to September 30,2014 for antenatal care and underwent one step screening for thyroid diseases in first trimester,which meant blood test for thyroid stimulating hormone(TSH),free thyroxine(FT4) and thyroid peroxidase antibody(TPOAb) at the same time.Simulation analysis was performed on these 4 044 women with twostep screening (TSH first and then FT4 and TPOAb if TSH was abnormal).The incidence,missed diagnosis rate,costs of screening,and outcomes of the missed diagnosed cases of women with thyroid diseases were compared between one-step and two-step screening based on the cutoff value determined by American Thyroid Association (ATA) or our hospital (0.23-4.08 mU/L).The positivel rate of TPOAb was compared among the three groups classified according to TSH value (≥ 0.1-＜ 2.5 mU/L,≥ 2.5-＜ 4.08 mU/L and ≥ 4.08 mU/L).T-test,Chi-square test or Fisher's exact test were applied for statistical analysis.Results When the cutoff value of TSH was set at ≥ 0.1-＜ 2.5 mU/L (ATA recommendation),7.9％ (320/4 044) of the women required medical treatment.It was significantly higher than 3.2％ (129/4 044),which was obtained when the normal reference value of TSH was set based on data from our hospital.The positive rates of TPOAb were 7.2％(214/2 976),13.9％(103/777) and 28.6％(55/192) for TSH ≥ 0.1-＜ 2.5,≥ 2.5-＜ 4.08 mU/L and ≥ 4.08 mU/L group,respectively.When we set the OR value for TOPAb as one in the TSH ≥ 0.1-＜ 2.5 mU/L group,the OR(95％C1)s of the other two groups were 1.972(1.537-2.532) and 5.181(3.679-7.297).If two-step screening protocol and ATA recommendations were applied,0.7％ (27/4 044) of women who needed treatment would be missed.However,312 480 yuan (RMB) would be saved compared with one-step screening (77.27 yuan per person).When the hospitalized reference value was applied,1.1％(45/4 044) of women would not be treated and 384 720 yuan would be saved (95.13 yuan per person) compared to one-step screening.For those missed diagnosed cases,no more adverse pregnant outcomes (all P＞0.05),including fetal distress,gestational diabetes mellitus,preterm birth,fetal growth restriction,oligohydroamnios,polyhydroanmios,fetal death,gestational hypertension with pre-eclampsia,placental abruptio and neonatal asphyxia were reported although no standard treatment had been provided,no matter ATA recommendation or unique reference in our hospital was adopted.Conclusions We recommend the two-step method for thyroid function screening during early pregnancy.For the purpose of cost-saving,reduction of missed diagnosis rate and avoidance of overtreatment,the management protocol should be individualized for those women with TSH value between 2.5 mU/L and the normal reference value of our hospital during pregnancy.